<template>
    <div class="app-container">
        <h2 style="text-align: center;">发布新课程</h2>
        <el-steps :active="1" process-status="wait" align-center style="margin-bottom: 40px;">
        <el-step title="填写课程基本信息"/>
        <el-step title="创建课程大纲"/>
        <el-step title="最终发布"/>
        </el-steps>

        <el-form label-width="120px">
            <el-form-item label="课程标题">
                <el-input v-model="courseInfo.title" placeholder=" 示例：机器学习项目课：从基础到搭建项目视频课程。专业名称注意大小写"/>
            </el-form-item>

            <!-- 所属分类 TODO -->
            <el-form-item label="课程分类">
                <!-- 一级分类 -->
                <el-select v-model="courseInfo.subjectParentId" placeholder="一级分类" @change="subjectLevelOneChange">
                    <el-option 
                        v-for="subject in subjectOneList"
                        :key="subject.id"
                        :label="subject.title" 
                        :value="subject.id">
                    </el-option>
                </el-select>

                <!-- 二级分类 -->
                 <el-select v-model="courseInfo.subjectId" placeholder="二级分类">
                    <el-option 
                        v-for="subject in subjectTwoList"
                        :key="subject.id"
                        :label="subject.title" 
                        :value="subject.id">
                    </el-option>
                </el-select>
            </el-form-item>

            <!-- 课程讲师 TODO -->
            <el-form-item label="课程讲师">
                <el-select v-model="courseInfo.teacherId" placeholder="请选择">
                    <el-option 
                        v-for="teacher in teacherList"
                        :key="teacher.id"
                        :label="teacher.name" 
                        :value="teacher.id">
                    </el-option>
                </el-select>
            </el-form-item>

            <el-form-item label="总课时">
                <el-input-number :min="0" v-model="courseInfo.lessonNum" controls-position="right" placeholder="请填写课程的总课时数"/>
            </el-form-item>

            <!-- 课程简介 TODO -->
            <el-form-item label="课程简介">
                <tinymce :height="300" v-model="courseInfo.description" />
            </el-form-item>

            <!-- 课程封面 TODO -->
            <el-form-item label="课程封面">
                <el-upload
                    :show-file-list="false"
                    :on-success="handleAvatarSuccess"
                    :before-upload="beforeAvatarUpload"
                    :action="BASE_API+'/eduoss/fileoss/upload'"
                    class="avatar-uploader">
                    <img :src="courseInfo.cover">
                </el-upload>
            </el-form-item>

            <el-form-item label="课程价格">
                <el-input-number :min="0" v-model="courseInfo.price" controls-position="right" placeholder="免费课程请设置为0元"/> 元
            </el-form-item>

            <el-form-item>
                <el-button :disabled="saveBtnDisabled" type="primary" @click="saveOrUpdate">保存并下一步</el-button>
            </el-form-item>
        </el-form>
    </div>
</template>
<script>
    import courseApi from '@/api/edu/course'
    import subjectApi from '@/api/edu/subject'
    //引入富文本组件
    import tinymce from '@/components/Tinymce'

    export default {
        //声明组件
        components: { tinymce },
        data() {
            return {
                saveBtnDisabled: false, // 保存按钮是否禁用
                courseInfo: {
                    title: '',
                    subjectId: '',  //二级分类id
                    subjectParentId: '',    //一级分类id
                    teacherId: '',
                    lessonNum: 0,
                    description: '',
                    cover: '/static/bns.jpg',    //默认图片
                    price: 0
                },
                courseId: '',
                BASE_API: process.env.BASE_API,     //接口API地址
                teacherList: [], //封装所有的讲师
                subjectOneList: [],  //封装一级分类
                subjectTwoList: []  //封装二级分类
            }
        },
        watch: {   //路由监听
            $route(to, form){  //路由发生变化，方法就会执行
                this.courseInfo = {
                    title: '',
                    subjectId: '',  //二级分类id
                    subjectParentId: '',    //一级分类id
                    teacherId: '',
                    lessonNum: 0,
                    description: '',
                    cover: '/static/bns.jpg',    //默认图片
                    price: 0
                }
            }
        },
        created() {
            //根据路由id，(便于后面查询数据回显)
            if(this.$route.params && this.$route.params.id) {
                this.courseId = this.$route.params.id
                //调用根据id查询课程的方法
                this.getInfo()
            }else {
                //初始化所有讲师
                this.getListTeacher()
                //初始化一级分类
                this.getOneSubject()
                //初始化
                this.init()
            }
        },
        methods: {
            init() {
                //判断路径中是否有id值
                if(this.$route.params && this.$route.params.id){
                    //从路径中获取id值
                    const id = this.$route.params.id
                    //调用根据id查询的方法
                    this.getCourseInfoId(id)
                }else {
                    //清空表单
                    this.courseId = {}
                }
            },
            //根据课程id查询信息
            getInfo() {
                courseApi.getCourseInfoId(this.courseId)
                    .then(response => {
                        //在courseInfo会有课程信息，里面包含一级分类和二级分类
                        this.courseInfo = response.data.courseInfoVo
                        //查询出所有的分类
                        subjectApi.getSubjectList()
                            .then(response => {
                                //获取所有的一级分类
                                this.subjectOneList = response.data.list
                                //把所有一级分类数组进行遍历
                                for(var i = 0; i < this.subjectOneList.length; i++) {
                                    //获取每个一级分类
                                    var oneSubject = this.subjectOneList[i]
                                    //比较当前courseInfo里面一级分类id和所有的一级id
                                    if(this.courseInfo.subjectParentId === oneSubject.id) {
                                        //获取一级分类下所有的二级分类
                                       this.subjectTwoList = oneSubject.children
                                    }
                                }
                            })
                            //初始化所有讲师
                            this.getListTeacher()
                    })
            },
            //上传之前调用的方法
            beforeAvatarUpload(file) {
                const isJPG = file.type === 'image/jpeg'
                const isLt2M = file.size / 1024 / 1024 < 2
                if (!isJPG) {
                    this.$message.error('上传头像图片只能是 JPG 格式!')
                }
                if (!isLt2M) {
                    this.$message.error('上传头像图片大小不能超过 2MB!')
                }
                return isJPG && isLt2M
            },

            //上传封面成功调用的方法
            handleAvatarSuccess(response, file) {
                this.courseInfo.cover = response.data.url
            },

            //点击一级分类，触发change事件，显示对应二级分类
            subjectLevelOneChange(value) {
                //value 是一级分类的id值
                //便利所有分类，包含一级和二级
                for(var i = 0; i < this.subjectOneList.length; i++) {
                    //每个一级分类
                    var oneSubject = this.subjectOneList[i]
                    //判断一级分类id和点击一级分类id是否一样
                    if(oneSubject.id === value) {
                        //从一级分类获取里面所有的二级分类
                        this.subjectTwoList = oneSubject.children
                        //把二级分类id值清空
                        this.courseInfo.subjectId = ''
                    }
                }
            },

            //查询所有的一级分类
            getOneSubject() {
                subjectApi.getSubjectList()
                    .then(response => {
                        this.subjectOneList = response.data.list
                    })
            },

            //查询所有讲师
            getListTeacher() {
                courseApi.getListTeacher()
                    .then(response => {
                        this.teacherList = response.data.items
                    })
            },

            //添加课程
            addCourse() {
                courseApi.addCourseInfo(this.courseInfo)
                    .then(response => {
                        //提示
                        this.$message({
                            type: 'success',
                            message: '添加课程信息成功!'
                        })
                         //跳转到第二步
                        this.$router.push({path:'/course/chapter/'+response.data.courseId})
                    })
            },

            //修改课程
            updateCourse() {
                courseApi.updateCourseInfo(this.courseInfo)
                    .then(response => {
                         //提示
                        this.$message({
                            type: 'success',
                            message: '修改课程信息成功!'
                        })
                         //跳转到第二步
                        this.$router.push({path:'/course/chapter/'+this.courseId})
                    })
            },

            saveOrUpdate() {
                if(this.courseInfo.title === ''){
                    this.$message.error('请输入课程信息!')
                    return;
                }
                //判断是修改还是添加
                if(!this.courseInfo.id) {
                    this.addCourse()
                }else {
                    this.updateCourse()
                }
            }
        }
    }
</script>

<!-- 样式 -->
<style scoped>
    .tinymce-container {
        line-height: 29px;
    }
</style>